More on Separation

glass tubing rubber

stopper

Salt water

hot plate

glass tubing

flask

rubber stopper

Salt water

hot plate

plastic tubing

beaker

Distillation

#1 The salt

water boils

#2 Only the water evaporates

#3 the water condenses

…

#4 … and collects in the tube

#5 which then runs into the cup.

Liquid

Gas

Liquid Again

• Imagine you are stranded on a deserted island and you look down beside you and find a piece of clear plastic!

• How might you clean the salty water so that you can drink it??

Solar Still

Video

In the natural environment, there are many other substances in water – not just salt

Not Just Salt …

• As rainwater runs over rocks and soil, minerals are dissolved and carried away in solution.

NitrogenPhosphorousPotassiumCalciumMagnesiumCopperZincIron

• Water that contains a lot of dissolved minerals is called hard water.

• Hard water is natural and safe to drink.

• But: - more soap to lather- soap scum on baths- ‘scaling’ in kettles

• Water that contains few dissolved minerals is called soft water.

- rainwater

- distilled water